Re: [Elecraft] KX3 External Transverter and ATU TUNE disable optionsuggestion
Don, That makes sense too, thanks. I still would like to have an option of a tap off the low power drive before the PA with the PA disabled when using an external transverter, so that I could have the benefit of controllable low power with low wideband transmitted noise and no heat problems at high duty cycle. 73 David Anderson GM4JJJ > On 5 Jan 2014, at 20:17, Don Wilhelm wrote: > > David, > > I don't know about the power control characteristics of the KX3 yet, but with > the K2 without the K60XV option), more steady power control is achieved in > the 2 to 10 watt range as compared to lower power levels. It all has to do > with resolution - the power is set in 0.1 watt increments, and an uncertainty > of 1 count can double or halve the power level at very low values, but that > same uncertainty is much less at 2 watts and even less at 4 watts. > > For JT65 and other long transmission full duty cycle periods, the heat > dissipation must be considered if you want to prolong the life of the finals > - so use 2 or 3 watts. > > 73, > Don W3FPR > >> On 1/5/2014 2:42 PM, David Anderson wrote: >> David, >> >> I have a further thought about the difficulties of using the KX3 with an >> external transverter, if we reduce the maximum power output for the XVTR by >> using the XV PWR H setting to say a very low value (say the lowest which is >> 0.1 Watt), then is there a danger that the relative transmitted wideband >> amplifier noise will be higher than if we kept the power at say 4 Watts and >> then used a big attenuator on the input of the TX port on the transverter? >> >> All my previous experience with transverters have been with radios that had >> dedicated low power transverter RF out ports. Even then there were problems >> with thermal power drift, excessive drive levels due to lack of the normal >> ALC that radio normally depended on when using it on HF etc. >> >> I presume that there is no way to easily bypass the PA and driver stages >> within the KX3 to get lower drive power without reducing the TX gain. I have >> been looking at the KX3 schematics trying to work out where the as yet >> unreleased KX3 internal 2m transverter gets it drive from and at what level >> that is. >> >> Perhaps Elecraft may give us some clues or guidance. >> >> What would be neat, but it don't suppose we can expect Elecraft to do it, >> would be a board that would replace the planned internal 2m transverter, and >> would just act as a lower power transverter output from before the PA >> stages, on an SMA connector where the 2m antenna socket will be, with the >> main antenna BNC as a receive only port, (though that could be dangerous), >> perhaps a low power TX/RX on the SMA would be best. >> >> 73 >> >> David Anderson GM4JJJ > > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] KX3 External Transverter and ATU TUNE disable optionsuggestion
David, I don't know about the power control characteristics of the KX3 yet, but with the K2 without the K60XV option), more steady power control is achieved in the 2 to 10 watt range as compared to lower power levels. It all has to do with resolution - the power is set in 0.1 watt increments, and an uncertainty of 1 count can double or halve the power level at very low values, but that same uncertainty is much less at 2 watts and even less at 4 watts. For JT65 and other long transmission full duty cycle periods, the heat dissipation must be considered if you want to prolong the life of the finals - so use 2 or 3 watts. 73, Don W3FPR On 1/5/2014 2:42 PM, David Anderson wrote: David, I have a further thought about the difficulties of using the KX3 with an external transverter, if we reduce the maximum power output for the XVTR by using the XV PWR H setting to say a very low value (say the lowest which is 0.1 Watt), then is there a danger that the relative transmitted wideband amplifier noise will be higher than if we kept the power at say 4 Watts and then used a big attenuator on the input of the TX port on the transverter? All my previous experience with transverters have been with radios that had dedicated low power transverter RF out ports. Even then there were problems with thermal power drift, excessive drive levels due to lack of the normal ALC that radio normally depended on when using it on HF etc. I presume that there is no way to easily bypass the PA and driver stages within the KX3 to get lower drive power without reducing the TX gain. I have been looking at the KX3 schematics trying to work out where the as yet unreleased KX3 internal 2m transverter gets it drive from and at what level that is. Perhaps Elecraft may give us some clues or guidance. What would be neat, but it don't suppose we can expect Elecraft to do it, would be a board that would replace the planned internal 2m transverter, and would just act as a lower power transverter output from before the PA stages, on an SMA connector where the 2m antenna socket will be, with the main antenna BNC as a receive only port, (though that could be dangerous), perhaps a low power TX/RX on the SMA would be best. 73 David Anderson GM4JJJ __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] KX3 External Transverter and ATU TUNE disable optionsuggestion
David, I have a further thought about the difficulties of using the KX3 with an external transverter, if we reduce the maximum power output for the XVTR by using the XV PWR H setting to say a very low value (say the lowest which is 0.1 Watt), then is there a danger that the relative transmitted wideband amplifier noise will be higher than if we kept the power at say 4 Watts and then used a big attenuator on the input of the TX port on the transverter? All my previous experience with transverters have been with radios that had dedicated low power transverter RF out ports. Even then there were problems with thermal power drift, excessive drive levels due to lack of the normal ALC that radio normally depended on when using it on HF etc. I presume that there is no way to easily bypass the PA and driver stages within the KX3 to get lower drive power without reducing the TX gain. I have been looking at the KX3 schematics trying to work out where the as yet unreleased KX3 internal 2m transverter gets it drive from and at what level that is. Perhaps Elecraft may give us some clues or guidance. What would be neat, but it don't suppose we can expect Elecraft to do it, would be a board that would replace the planned internal 2m transverter, and would just act as a lower power transverter output from before the PA stages, on an SMA connector where the 2m antenna socket will be, with the main antenna BNC as a receive only port, (though that could be dangerous), perhaps a low power TX/RX on the SMA would be best. 73 David Anderson GM4JJJ > On 5 Jan 2014, at 11:06, "Dave" wrote: > > I'll second Davids request. I have some transverters that will take a fair > amount of RF in, like the Spectrum Communications types, but others expect > quite low levels of RF input and, like the other David, I would be bound to > forget to turn the internal ASTU off one day... > > Dave (G0DJA) > > - Original Message - From: "David Anderson" Sent: Sunday, January 05, > 2014 10:39 AM > Subject: Re: [Elecraft] KX3 External Transverter and ATU TUNE disable > optionsuggestion > > >> Hi Don, >> >> Thanks for that. >> >> I was not referring specifically to the Elecraft XV series of transverters, >> as I have plans to rebuild my home built transverter for 144 MHz. So this >> was a general comment for those who want to use external transverters with >> their KX3, as I imagine quite a few may do given the high performance of the >> radio in such a small package. >> >> Some thought had gone in to supporting transverters by Elecraft with XV >> offset and XV H power limit and other very useful parameters that can be >> set, however having to use a large drive power of 4 watts and then attenuate >> it to a few mW for the transverter mixer is against the QRP principles, and >> for high duty cycle modes like JT65 is a non starter given the undersized >> heatsink on the KX3. >> >> One small change in the KX3 firmware to automatically put the ATU mode into >> BYPASS MODE when an XV is selected would solve this potential problem >> elegantly. Pretty please! > > __ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] KX3 External Transverter and ATU TUNE disable optionsuggestion
I'll second Davids request. I have some transverters that will take a fair amount of RF in, like the Spectrum Communications types, but others expect quite low levels of RF input and, like the other David, I would be bound to forget to turn the internal ASTU off one day... Dave (G0DJA) - Original Message - From: "David Anderson" Sent: Sunday, January 05, 2014 10:39 AM Subject: Re: [Elecraft] KX3 External Transverter and ATU TUNE disable optionsuggestion Hi Don, Thanks for that. I was not referring specifically to the Elecraft XV series of transverters, as I have plans to rebuild my home built transverter for 144 MHz. So this was a general comment for those who want to use external transverters with their KX3, as I imagine quite a few may do given the high performance of the radio in such a small package. Some thought had gone in to supporting transverters by Elecraft with XV offset and XV H power limit and other very useful parameters that can be set, however having to use a large drive power of 4 watts and then attenuate it to a few mW for the transverter mixer is against the QRP principles, and for high duty cycle modes like JT65 is a non starter given the undersized heatsink on the KX3. One small change in the KX3 firmware to automatically put the ATU mode into BYPASS MODE when an XV is selected would solve this potential problem elegantly. Pretty please! __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
